The objective of this program is to spatially map isolated, perfused rat hearts using nuclear magnetic resonance (NMR). The NMR procedure is designed to spatially discriminate between normal and ischemic myocardial regions both in time and space using the already shown variation of T1 (the NMR spin-lattice relaxation time) with respect to the spatial variation of the state of ischemia. The goal is to acquire a two-dimensional map in less than four minutes. The necessary equipment has been acquired and the NMR procedure has advanced so that mappings of static objects have been obtained. The experiments planned will be directed toward ascertaining the mapping discrimination between normal, ischemic, and infarcted regions and determining the limits on spatial resolution. The tissue types will be validated histologically.